What is the ruling on combining prayers due to fear of raids, or instability, or moving to participate in battle, or traveling between countries to serve the sick and provide relief?

Many scholars have held the view that fear is a valid excuse permitting a resident to combine prayers, citing the hadith (definition) of Ibn Abbas that the Prophet, peace and blessings be upon him, combined prayers in Medina when there was no fear and no rain, intending thereby not to cause hardship to his Ummah. According to this view, it is permissible for the people of Syria to combine prayers due to fear of bombing or the enemy. The same applies to those who move to serve the Mujahideen or the wounded if hardship is present. However, it is more cautious to avoid combining prayers to exit the disagreement.